Antimicro bial Activity of some 13-Alkyl Substituted Proto berberinium salts Kinuko Iwasa, Miyoko Kamigauchi, Makiko Sugiura, and Hiroaki Nanba Abstract: Several 13-alkyl substituted analogs of berberine and palmatine were found to be highly active against two types of Staphylococcus aureus(SI and S2)of different origin. The most active 13-hexylberberine was 8 times more active(against SI)and the same order active(against S2)as kanamycin sulfate. 13-Hexylpatmatine displayed an activety against S aureus(S1)4 times greater than that of kanamycin sulfate. The activities of 13-hexylberberine against two types of S aureus were 64 and 128 times greater than those of the clinically used alkaloid berberine Additionally two hexyl derivatives possessed antifungal activity Key words: 13-Alkylrotoberinium salts, antimicrobial activity, antifungal activity. Introduction The quaternary is quinoline alkaloid berberine(1), isolated from a variety of plants, is widely used in Asia as a drug due to its antimicrobial activity. In Japan, berberine and the extracts of the dried rhizomes of Coptis japonica Makino( Ranunculaceae) and the dried bark of phellodendron amurense Ruprecht ( Rutaceae )are widely used as a stomach tonic. In a previous paper the antibacterial activity of berberine analogs has been reported (1). In brief, th derivative(2), the 13-ethyl analog(3), and the 13-ethyl-g-ethoxy homolog( 4 )displayed an increase in antibacterial activity against Staphylococcus aureus by factors of 2, 4, and 8, respectively, over the parent salt berberine. These results strongly suggested that the bulk of the alkoxy- and alkyl-substituents at C-9 and C-13 had a direct bearing upon the activity Results and discussion In the present work, the effects of variations in the length of the alkyl sidechain at C-13 on the antimicrobial activity were examined in both berberine(1)and palmatine( 8 )derivatives. Some known and some new substances(1-4, 8, 9, and5-7, 10-13)were tested against representative strains of Gram-positive, Gram-negative and fungal microorganisms by the 2-fold dilution techniques Two types of S aureus(SI and S2), as well as Escherichia coli, and Candida albicans were used The propyl-, butyl-, and hexyl-substituted derivatives at C-13 of berberine( 1)or palmatine(8)and 13-ethylpalmatine were prepared by treatment of the parent alkaloid with propionaldehyde, n-butylaldehyde, n-hexylaldehyde, and acetaldehyde, respectively e structures of these compounds(5-7 and 10-13)were confirmed by means of 1H-and C-NMR data including NOESY, DEPT, COSY, HMBC, and HMQC spectral data. These data enabled us also to assign the H-and C-NMr spectra unambiguously as shown in Tables I and 2. The mass spectra of all the new compounds were consistent with the assigned structures(Table 3).The retention times of the 13-alkyl derivatives in HPLC increased with increasing length of the alkyl sidechain at C-13(Table 3)Antimicrobial Activity of Some 13-Alkyl Substituted Protoberberinium Salts Kinuko Iwasa,Miyoko Kamigauchi,Makiko Sugiura,and Hiroaki Nanba Abstract: Several 13-alkyl substituted analogs of berberine and palmatine were found to be highly active against two types of Staphylococcus aureus (S1 and S2)of different origin. The most active 13-hexylberberine was 8 times more active (against S1)and the same order active (against S2)as kanamycin sulfate.13-Hexylpatmatine displayed an activety against S.aureus(S1)4 times greater than that of kanamycin sulfate. The activities of 13-hexylberberine against two types of S.aureus were 64 and 128 times greater than those of the clinically used alkaloid berberine. Additionally two hexyl derivatives possessed antifungal activity. Key words:13-Alkylrotoberinium salts, antimicrobial activity, antifungal activity. Introduction The quaternary is oquinoline alkaloid berberine(1),isolated from a variety of plants, is widely used in Asia as a drug due to its antimicrobial activity. In Japan, berberine and the extracts of the dried rhizomes of Coptis japonica Makino (Ranunculaceae) and the dried bark of phellodendron amurense Ruprecht (Rutaceae)are widely used as a stomach tonic. In a previous paper the antibacterial activity of berberine analogs has been reported (1).In brief, the 13-methyl derivative(2) ,the 13-ethyl analog(3),and the 13-ethyl-9-ethoxy homolog(4) displayed an increase in antibacterial activity against Staphylococcus aureus by factors of 2,4,and 8,respectively,over the parent salt berberine. These results strongly suggested that the bulk of the alkoxy- and alkyl-substituents at C-9 and C-13 had a direct bearing upon the activity. Results and Discussion In the present work, the effects of variations in the length of the alkyl sidechain at C-13 on the antimicrobial activity were examined in both berberine(1) and palmatine (8)derivatives. Some known and some new substances (1-4,8,9,and5-7,10-13)were tested against representative strains of Gram-positive, Gram-negative and fungal microorganisms by the 2-fold dilution techniques. Two types of S.aureus(S1 and S2),as well as Escherichia coli, and Candida albicans were used. The propyl-, butyl-,and hexyl-substituted derivatives at C-13 of berberine(1) or palmatine(8) and 13-ethylpalmatine were prepared by treatment of the parent alkaloid with propionaldehyde, n-butylaldehyde, n-hexylaldehyde, and acetaldehyde, respectively. The structures of these compounds(5-7 and 10-13)were confirmed by means of 1H-and 13C-NMR data including NOESY, DEPT, COSY, HMBC, and HMQC spectral data. These data enabled us also to assign the 1H-and 13C-NMR spectra unambiguously as shown in Tables 1 and 2.The mass spectra of all the new compounds were consistent with the assigned structures (Table 3).The retention times of the 13-alkyl derivatives in HPLC increased with increasing length of the alkyl sidechain at C-13(Table 3)